Case fatality rate climbs to nearly 48 percent in the DRC, meaning almost one in two people infected with Ebola are dying.

The Ebola outbreak in the Democratic Republic of the Congo (DRC) has reached  5,515 confirmed cases of infection and killed 2,642 people, with 51 new cases detected in Ituri and North Kivu provinces, according to the latest government figures.

The update on Sunday came as Pope Leo called for ⁠international action to help contain the epidemic, which is now the deadliest Ebola outbreak in the DRC’s history.

Declared in mid-May, it is the DRC’s 17th Ebola epidemic and was designated a Public Health Emergency of International Concern by the World Health Organization (WHO), its highest alert level, also covering neighbouring Uganda.

The outbreak is now on track to surpass the deadliest Ebola epidemic on record, which was the 2014–2016 outbreak in West Africa that killed more than 11,000 people.

According to government figures, the case fatality rate in the DRC has climbed from about 20 percent in early June to nearly 48 percent now, meaning almost one in two people infected are dying.

Contact tracing, however, has improved sharply, from 30 percent in June to more than 85 percent.

The disease has also proved deadly for those fighting it. About 160 health workers have been infected, and about 45 have died, according to the WHO.

Efforts to contain the outbreak, however, have been hampered by armed conflict in the affected provinces, displacement, attacks on medical personnel and facilities, a mobile working population and a lack of critical infrastructure.

Vaccines arrive in DRC

There is no approved vaccine or treatment for this particular strain of Ebola, known as Bundibugyo, which is rarer than the virus type behind most past outbreaks.

The WHO has pledged 70,000 doses of the Ervebo vaccine, which is licensed for Ebola and has been effective in past outbreaks. According to the global body, early data from animal trials suggest it may offer some protection against Bundibugyo.

Some 16,250 doses of the vaccine arrived in the DRC on Friday.

WHO Director-General Tedros Adhanom Ghebreyesus and other officials said the response in the DRC needs to be scaled up two to threefold to contain the outbreak and reach every affected area.

They also called for more support and protection for front-line health workers, including protective equipment, timely payment, and access to rapid diagnosis and high-quality supportive care if they fall ill.

Abdulsalami Nasidi, a public health consultant who helped establish the Africa Centres for Disease Control and Prevention, told Al Jazeera that the outbreak was “getting out of hand”.

He blamed weak infection control measures and a lack of trust between authorities and affected communities for the continued transmission.

“This is no longer just a national or regional issue; it is a global issue. If it spreads to neighbouring places with lower immunity, it will be a disaster,” Nasidi added.

The WHO currently rates the risk to the global public as low, but warns that the danger inside the DRC remains very high.

Despite the surging cases, Uganda and several health zones in DRC’s Ituri and South Kivu have interrupted transmission, which the WHO said is evidence that rapid detection, decisive leadership, and community cooperation can break the chain of transmission.

At the Vatican on Sunday, Pope Leo offered prayers for the DRC, “in light of the spread of the Ebola epidemic, which is sadly ⁠claiming many lives”.

The pontiff also called for global action to help save lives.

“I urge the international community to ⁠respond in a way that also involves local communities ⁠in prevention efforts to save ⁠as many lives as possible,” he said.